1. Field of the Invention
The present invention generally relates to an apparatus for data storage and retrieval. Specifically, the invention is an apparatus for moving and positioning a read/write head relative to the surface of a storage element.
2. Background
Advances in computer hardware continue to increase storage capacity of optical-based and magnetic-based media and to minimize shock and vibration effects impeding data storage and retrieval. However, little progress has been realized in terms of reducing the time interval required to move a read/write head from its original location and to position it above a new location along a storage element for the purpose of writing and retrieving data.
Head movement and positioning is traditionally performed via a mechanically controlled arm having one or more read/write heads. For example, Battu et al., U.S. Pat. No. 5,841,610, describes a positioning device comprising a mechanical arm rotatably controlled by voice coil motor. McKay et al., U.S. Pat. No. 5,761,005, describes a positioning device comprising a mechanical arm linearly extendible by motor. Both inventions are inherently slow, since each requires the mechanical movement of a relatively large arm above a storage element, specifically a magnetic disk or platter.
Active materials, one example being a piezoelectric, mechanically distort or resonate when energized. While traditional piezoelectric materials facilitate rapid movement, such movement is coarse and therefore not compatible with head positioning over a large area. However, piezo-based actuators capable of micro-positioning are described in the related arts. Magee et al., U.S. Pat. No. 6,078,476, describes an improved rotating mechanical arm driven by a voice coil motor wherein a read/write head is accurately positioned via micro-actuators attached to the arm Cini et al., U.S. Pat. No. 6,259,584, describes and claims a rotatable micro-positioning device attachable to a mechanical arm. Fiske, U.S. Pat. No. 6,078,471, describes a fixed length head array movably positioned above a platter via an actuator.
High-bandwidth piezoelectric, piezoceramic, electrostrictive, magnetostrictive, and electrostatic materials are both sufficiently robust to move and sufficiently precise to position a read/write head. The application of such materials along the length of a head positioner apparatus offers the unique capability of both rapid and controlled movement of a read/write head, rather than the mechanical movement of a read/write head attached to a large arm as described in Battu et al., McKay et al., Magee et al., and Cini et al. Furthermore, high-bandwidth materials enable both rapid and precise movement, yet provide the flexible positioning of one or more read/write heads lacking in Fiske.
It is therefore an object of the present invention to avoid the disadvantages of the related art. More particularly, it is an object of the invention to provide a head positioner apparatus decreasing total access time of a read/write head across a storage element.
The present invention provides for the slidable movement and positioning of one or more read/write heads driven by the activation of a piezoelectric, piezoceramic, electrostrictive, magnetostrictive, or electrostatic material disposed along a rail. In this context, sliding and slidable movement of positioner along driver arm are broadly construed to include, but not limited to, continuous and near continuous contact between driver arm and positioner, as well as translational displacement with little or no contact between positioner and driver arm The invention is applicable to both magnetic and optical storage devices.
The preferred apparatus consists of a driver arm, a positioner, and at least one read/write head. Driver arm is composed of a rail having two planar guides lengthwise fixed and perpendicular to a planar cross member. An isolator layer is lengthwise attached to both planar surfaces of said cross member and is composed of a material preventing distortion of the rail when driver layer is activated. A driver layer is attached lengthwise to each isolator layer opposite of the cross member and is composed of a material that mechanically distorts or resonates, generates an electric field, or generates a magnetic field when energized. Thereafter, a wear resistant layer is attached lengthwise to each driver layer and opposite of the isolator layer. Positioner is slidably disposed along said driver arm and secured to at least one guide. Positioner is propelled along driver arm when driver layer is energized and stationary when energy is removed. At least one read/write head is fixed to the positioner for data communication purposes with a storage element.
In an alternate embodiment, a pair of positioners are independently movable along a single driver arm. Driver arm is composed of a rail having two planar guides lengthwise fixed and perpendicular to a planar cross member. An isolator layer is attached lengthwise to each side of the cross member and is composed of a material preventing distortion of the rail when driver layer is activated. A pair of driver layers is separably attached lengthwise to each isolator layer opposite of said cross member and is composed of a material that mechanically distorts or resonates, generates an electric field, or generates a magnetic field when energized. Thereafter, a wear resistant layer is separably attached lengthwise to each driver layer and opposite of the isolator layer. A pair of positioners are slidably and separately disposed along the driver arm. A positioner is movably secured to each guide comprising the rail. A positioner is propelled along the driver arm when at least one driver layer is energized and stationary when energy is removed. At least one read/write head is fixed to each positioner to access data on one or more storage elements.
The described and claimed invention facilitates rapid yet independent movement of one or more read/write heads across a storage element. The primary benefits are reduced seek time and random track access in hard drive and optical disk applications.